ENH: Update PNG to v1.6.54

[blowekamp]

This PR updates the PNG (libpng) third-party library from version v1.6.44 to v1.6.54.

Summary

• Updated UpdateFromUpstream.sh to tag v1.6.54
• Ran the update script to merge upstream changes
• Resolved merge conflict in pngconf.h
• Updated symbol mangling for 10 new public API functions

Changes

• Version bump: v1.6.44 → v1.6.54 (10 minor releases)
• Security fixes and improvements from upstream
• Removed obsolete old Borland/MSVC compiler workarounds
• Bug fixes and performance improvements

Conflict Resolution

A merge conflict occurred in Modules/ThirdParty/PNG/src/itkpng/pngconf.h:

1. Top of file: Preserved ITK's #include "itk_png_mangle.h" which is critical for symbol mangling
2. DLL export block: Accepted upstream's removal of old Borland and early MSVC compiler workarounds, simplifying to modern __declspec(dllexport/dllimport) handling

Symbol Mangling Updates

Added 10 new public API functions to itk_png_mangle.h.in (new in v1.6.45–v1.6.54):

• png_get_cICP / png_set_cICP — ICC Profile chunk
• png_get_cLLI / png_set_cLLI / png_get_cLLI_fixed / png_set_cLLI_fixed — Content Light Level Information
• png_get_mDCV / png_set_mDCV / png_get_mDCV_fixed / png_set_mDCV_fixed — Mastering Display Color Volume

Notes

• Generated using the update-third-party skill
• All ITK-specific modifications preserved

Upstream releases: https://github.com/pnggroup/libpng/releases (v1.6.45 through v1.6.54)

[dzenanz]

PR description is good and so detailed that I suspect AI was involved in writing it. Did AI do anything else, such as resolve those merge conflicts?

[dzenanz]

Ah, I now notice "Generated using the update-third-party skill", after seeing it in #5865 too. Updating third party libraries was time consuming. I guess AI can help there. How much time do you devote to reviewing merge conflict resolution?

[blowekamp]

@dzenanz Please see #5867 for the Agent skill I work on while making the updates.

For libpng, I don't think there were any conflict. But with the skills instructions in pick up on the command in itk_png_mangle.h.in, and followed those to update the mangling.

In VS code I was able too see some of the conflict and the changes made. I am not sure I saw them all but with the provided instructions Clause Sonnet 4.5 seems to do a good job.